Composite Dust Core Particle Mix for High-Frequency Inductors
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Solution Overview
Problem
Inductors in electronic devices face challenges in maintaining high performance and efficiency under severe magnetic environments with high-frequency operations, requiring magnetic members with specific characteristics such as high relative permeability, high DC superimposition rated current, and low iron loss, which existing dust cores fail to adequately provide.
Innovation Solution
A dust core composed of soft magnetic metal powder with a specific mixture of crystalline and amorphous particles, where the median diameters and mass ratios of these particles are optimized to enhance relative initial permeability, reduce iron loss, and improve DC superimposition characteristics, thereby supporting high-frequency operations and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional dust core is used in an inductor, then the inductor can be manufactured with standard materials, but the inductor fails to maintain high performance in severe magnetic environments with high-frequency operations
Solution Approach 1:
The dust core uses a composite material consisting of both crystalline particles and amorphous particles mixed together. The crystalline particles provide high relative permeability while the amorphous particles contribute to low iron loss and high DC superimposition rated current. This composite structure enables the inductor to maintain excellent magnetic characteristics in severe magnetic environments with high-frequency operations.
Solution Approach 2:
The invention optimizes specific parameters of the dust core including the median diameter of crystalline particles (D50c: 1.3 μm or less), the median diameter of amorphous particles (D50a: 2.0 μm or more and 12.0 μm or less), and the mass ratio of crystalline to amorphous particles (Rc: 20% or more and 80% or less). These parameter optimizations enable the inductor to achieve high performance in severe magnetic environments while maintaining adaptability to high-frequency operations.
2Volume of moving object
If the inductor is miniaturized to meet size requirements, then the electronic device can be compacted, but the DC superimposition rated current decreases
Solution Approach 1:
The dust core employs a composite material of crystalline and amorphous particles where the amorphous particles play a crucial role in maintaining high DC superimposition rated current. This allows the inductor to be miniaturized while preserving the necessary current handling capability, as the amorphous phase provides excellent magnetic properties under DC bias conditions.
Solution Approach 2:
By optimizing the mass ratio of crystalline to amorphous particles (Rc: 20% or more and 80% or less) and controlling the particle size distribution, the invention achieves a balance between miniaturization and DC superimposition rated current. The specific parameter ranges enable the inductor to maintain high current capability in a compact form factor.
3Volume of moving object
If the inductor operates at high frequency to reduce size, then the switching power source circuit can be compacted, but the iron loss increases
Solution Approach 1:
The dust core uses a composite material where amorphous particles contribute significantly to reducing iron loss at high frequencies. The amorphous phase has superior magnetic properties that minimize energy losses during high-frequency switching operations, enabling the inductor to operate efficiently at high frequencies without excessive iron loss.
Solution Approach 2:
The invention optimizes the median diameter of amorphous particles (D50a: 2.0 μm or more and 12.0 μm or less) and the mass ratio parameter (Ra: 20% or more and 80% or less) to minimize iron loss at high frequencies. These parameter optimizations enable the inductor to operate at high frequencies with reduced energy losses, facilitating circuit miniaturization.
4Quantity of substance
If the relative permeability is increased to improve inductance, then the inductance value increases, but the iron loss increases
Solution Approach 1:
The dust core employs a composite material where crystalline particles provide high relative permeability for increased inductance, while amorphous particles contribute to low iron loss. This division of functional roles within the composite material allows the inductor to achieve high inductance values without suffering from excessive iron loss, as each particle type compensates for the other's limitations.
Solution Approach 2:
The invention optimizes the mass ratio of crystalline to amorphous particles (Rc: 20% or more and 80% or less) to balance inductance and iron loss. By carefully controlling this ratio along with particle size parameters, the dust core achieves optimal performance where high relative permeability is maintained while iron loss is minimized, enabling efficient high-frequency operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The optimized dust core enhances the overall characteristic (μ2×Isat/Pcv) of inductors, enabling stable operation in severe magnetic environments with reduced iron loss and increased DC superimposition rated current, facilitating miniaturization and improved power efficiency.
Implementation Method 1
The dust core contains a soft magnetic metal powder, the soft magnetic metal powder containing a plurality of crystalline particles and a plurality of amorphous particles
Implementation Method 2
The crystalline particles have a composition containing Fe and Ni, and the median diameter D50 of the soft magnetic metal powder is calculated by formula (1) below and is 1.8 μm or more and 7.0 μm or less
Implementation Method 3
the inductor incorporated into the switching power source circuit is also required to be capable of being stably driven at a high frequency
Data Source
AI summary
A dust core includes a soft magnetic metal powder containing a plurality of crystalline particles and a plurality of amorphous particles. The median diameter D50c of the plurality of crystalline particles is 1.3 μm or less, and the median diameter D50a the plurality of amorphous particles is 2.0 μm or more and 12.0 μm or less. The median diameter D50 of the soft magnetic metal powder is calculated by a formula: D50=(Rc×D50c+Ra×D50a)/100, which is equal to or greater than 1.8 μm and equal to or smaller than 7.0 μm. In the formula, Rc is the mass ratio (unit: % by mass) of the plurality of crystalline particles relative to the soft magnetic metal powder, and Ra is the mass ratio (unit: % by mass) of the plurality of amorphous particles relative to the soft magnetic metal powder.